There have been two episodes of this Adult Swim show that featured infantilizing stories that seemed like they might be of interest to folks here. I should specify that no physical AR takes place and both episodes are pretty disturbing.

In "Be a Baby," John C. Reilly plays a guy who signs up for a weird infantilizing program he sees advertised on TV. It doesn't quite go the way he planned. This one is mostly about the poor guy being mistreated, and he gets diapered and stuff but he never regresses mentally: http://www.adultswim.com/videos/tim-erics-bedtime-stories/baby/